Add team name exception for I18n team

I18n team has an exceptional project name "I18n".
http://git.openstack.org/cgit/openstack/governance/tree/reference/projects.yaml#n937
It brings unintended capitalization "I18N" with Python title()
method. I18n is an abbreviation of internationalization,
so we should use the name "I18n".

Change-Id: Ibac3a78dbcb6bd5da9234c9fc39f6020b4e24c05

doc/source/_exts/teams.py

@@ -28,6 +28,8 @@ def _team_to_rst(name, info):
 
     if 'service' in info:
         title = "{0} ({1})".format(name.title(), info['service'])
+    elif name == 'I18n':
+        title = name
     else:
         title = name.title()